Spa base



FIG. 1 is a top, right, front perspective view of the spa base;

FIG. 2 is a top view of the spa base;

FIG. 3 is a bottom view of the spa base;

FIG. 4 is a right side view of the spa base;

FIG. 5 is a left side view of the spa base;

FIG. 6 is a rear view of the spa base;

FIG. 7 is a front view of the spa base; and,

FIG. 8 is a top, right, front perspective view of the spa base in its environment.

The broken lines showing a spa chair and foot rest are directed towards environmental subject matter, all other broken lines show portions of the spa base than form no part of the claimed design. 

CLAIM The ornamental design for a spa base, as shown and described. 